Workers who make and use rotation-transmitting devices know that they are apt to exhibit excessive "play", be too noisy, and involve sliding surfaces that are too readily contaminated by ambient dust and other fine abrasives. It is an object hereof to address such problems, providing rotation-transmission (e.g. less than 90.degree.), and especially in a device which transmits small rotary motion between parallel shafts with the use of offset flexures. Small motions here means rotations less than 90 degrees. A salient object is to transmit motion between parallel shafts with no backlash (i.e.; play) and no sliding motion surfaces that can be contaminated with dirt or other foreign objects.
This is preferably done via a paired-flexure array and the bending of flexures connecting rigid links fastened to each of two parallel shafts to allow rotary motion from one shaft to be transmitted to the other, without relative sliding between the flexure and shaft or other parts. This array can be operated at high rates of actuation because of the longitudinal sliding between the flexure and shaft or other parts. It can be operated at high rates of actuation because of the longitudinal stiffness of the flexures. Absence of backlash (i.e.; play) prevents lost motion and impacts which can cause acoustic noise.
Conventional means for transmitting motion between parallel shafts involve devices that have backlash (i.e.; play) which can be a source of acoustic noise, (e.g. from gears and linkages). Relative motion at the joints of these devices can also produce wear. The same is true of belt or cable couplings. Furthermore, these devices can easily be contaminated by foreign matter such as paper dust, sand, dirt, or other abrasive materials from environments in which these mechanisms may be required to operate. The use of seals to keep these contaminants out is cumbersome, and the seals themselves can be a source of wear. Adding seals to the coupling joints also adds mass, a detriment for high speed actuation. [e.g. see "Flexure devices--for economic action", Machine Devices and Instrumentation, NP Chironis, ed., McGraw-Hill, 1966, pp. 176-177, which shows motion devices using flexures but no paired-flexure couplings, as with this invention].
This invention gives a simple means of avoiding the above mentioned problems when small rotations are to be transmitted between parallel shafts. It can undergo an infinite number of actuations theoretically if the flexures are designed such that the stresses they experience are less than the endurance limit for their material. Steel, a common flexure material, may be used for example.
Thus, it is an object hereof to ameliorate (at least some of) such problems and to provide (at least some of) such advantageous features.